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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

24610 results found.

  1. GRB 250419A: Mephisto Multi-band Optical Detection
  2. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  3. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  4. EP250421a: NOT optical observations
  5. GRB 250419A: Optical Observations via Virtual Telescope Project
  6. EP250421a: REM optical upper limit
  7. EP250421A: COLIBRÍ Optical Upper Limit
  8. GRB 250419A: Mondy Continued Optical Observations
  9. GRB 250421B: AstroSat CZTI detection of a bright long burst
  10. EP250421a: Einstein Probe detection of an X-ray transient
  11. EP250421a: Mephisto optical counterpart confirmation
  12. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  13. EP250421a: JinShan likely optical counterpart
  14. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  15. GRB 250419A: LCO optical observation
  16. GRB 250419A: JinShan optical observations
  17. GRB 250419A: SVOM/C-GFT optical observations
  18. GRB 250419A: Swift/UVOT Follow up
  19. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  20. GRB 250419A: LCO optical afterglow multi-band observations
  21. GRB 250419A: Mondy and AbAO Optical Observations
  22. GRB 250419A: AKO Optical Afterglow Detection
  23. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  24. GRB 250419A: Swift-XRT refined Analysis
  25. GRB 250419A: KAIT optical afterglow observations
  26. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  27. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  28. GRB 250419A: SVOM detection of a soft burst
  29. EP250416a: Swift/XRT counterpart fading
  30. EP20250416a: Swift/XRT counterpart detection
  31. IceCube-250416A: DDOTI Optical Observations
  32. EP250416a: Gemini South-GMOS optical counterpart
  33. SVOM/sb25041603 is not a GRB
  34. EP250416a: GSP optical upper limit
  35. EP250416a: Einstein Probe detection of an X-ray transient
  36. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  37. SVOM/sb25041603: SVOM detection of an X-ray transient
  38. IceCube 250414.324: DDOTI Optical Observations
  39. GRB 250413A: AstroSat CZTI detection
  40. EP250304a: ATCA radio observations
  41. EP250404a: Nanshan 0.43m Telescope optical observatios
  42. GRB 250411A: DDOTI Optical Observations
  43. Fermi GRB 250411A: Global MASTER-Net observations report
  44. GRB 250407A: Continued KAIT/Nickel optical observations
  45. GRB 250314A: e-MERLIN observations
  46. GRB 250407A: Mondy and AbAO Optical Observations
  47. EP250227a: Further NOT optical observations
  48. GRB 250320B: cubesat Avion detection
  49. IceCube-250406A: Swift-XRT observations
  50. GRB 250407A: LCO detection of a fading optical counterpart
  51. Fermi-LAT gamma-ray observations of IceCube-250406A
  52. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  53. GRB 250407A: SVOM/GRM observation of a bright long burst
  54. GRB 250407A: EP-WXT afterglow detection
  55. EP250407a: EP-WXT detection of a fast X-ray transient
  56. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  57. GRB 250407A: KAIT Optical Afterglow Candidate
  58. IceCube-250406A: No candidates from the Zwicky Transient Facility
  59. GRB 250407A: Fermi GBM Detection
  60. GRB 250407A: Swift-XRT afterglow detection
  61. GRB 250407A: SRG/ART-XC afterglow detection
  62. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  63. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  64. IPN triangulation of GRB 250406B (short/hard)
  65. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  66. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  67. IceCube 250406.951: DDOTI Optical Observations
  68. GRB 250406A: AstroSat CZTI detection
  69. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  70. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  71. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  72. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  73. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  74. Konus-Wind detection of GRB 250404A / EP250404a
  75. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  76. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  77. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  78. EP250402a: Optical upper limit with PD 1.3m observations
  79. GRB 250404A / EP250404a: NOT optical observations
  80. GRB 250331D: Swift-XRT afterglow detection
  81. GRB 250404B: AstroSat CZTI detection of a short burst
  82. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  83. EP250404a: REM optical/NIR observations
  84. EP250404a: Seimei/TriCCS optical counterpart detection
  85. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  86. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  87. EP250404a: LCO optical counterpart detection
  88. EP250404a: Xinglong decaying optical counterpart
  89. GRB 250403A: Montarrenti Observatory optical detection
  90. GRB 250404A: Fermi GBM Detection
  91. GRB 250403A: KAIT optical observations
  92. EP250404a: AKO Optical Afterglow Detection
  93. EP250404a: LAST detection of optical counterpart
  94. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  95. GRB 250403A: Fermi GBM observations
  96. GRB 250327B: VIRT Optical Upper Limit
  97. EP250404a: Mephisto multi-band optical detection
  98. GRB 250331C Swift-BAT refined analysis
  99. GRB 250331B Swift-BAT refined analysis
  100. GRB 250330A Swift-BAT refined analysis

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